With the current computer diagnostics tests, it can take up to a minute per gigabyte to test the entire harddisk. Thus, it can be easily predicted that, as the hardfile sizes increase, the time to actually detect an error will become excessive. In fact, there are already problems where the user will not run diagnostics since it takes too long. What is needed is a method and structure to quickly selectively test the sectors on the hardfile or other computer storage devices to see if there are currently any problems.